Device for detecting physical quantity having a housing with a groove

ABSTRACT

A resistance heater  134  for detecting an air flow rate is supported by support members  134 A,  134 B. A housing  110  contains an electronic circuit  140  connected to the resistance heater  134 . The housing  110  is formed by integral molding with a terminal  142  for connecting the electronic circuit  140  to an external device. The terminal  142  is formed integrally with the housing  110 . The housing  110  has a groove  112  through which the terminal  142  is exposed in part.

TECHNICAL FIELD

The present invention relates to a device for detecting a physicalquantity, which detects a physical quantity such as an air flow rate ora pressure, and more particularly to a device for detecting a physicalquantity, which is suitable for detecting, e.g., a flow rate or apressure of air sucked into an internal combustion engine of anautomobile.

BACKGROUND ART

As one conventional device for detecting a physical quantity, asdisclosed in, for example, JP,A 3-233168, an air flowmeter with aresistance heater has a structure in which a housing section containingan electronic circuit is formed integrally with an auxiliary air passagesection, and the housing section and the auxiliary air passage sectionare arranged side by side on one plane. The air flowmeter is mounted toa body, in which an intake air passage of an internal combustion engineis formed, such that a flow rate detecting unit disposed in theauxiliary air passage section is located in the intake air passage.

DISCLOSURE OF THE INVENTION

When manufacturing a device for detecting a physical quantity, e.g., anair flowmeter, works for adjusting characteristics of the detectingdevice, such as sensitivity and 0-span, are required. These adjustmentworks require the flow rate detecting unit to be subjected to an actualairflow. To enable the adjustment works to start, it is thereforenecessary to, after almost completing the auxiliary air passage sectionincluding the flow rate detecting unit, mount the auxiliary air passagesection to equipment corresponding to the intake air passage and thenactually flow air.

Particularly, in an air flowmeter with a resistance heater, because ofthe necessity that a detector has a very small size and is electricallyconnected to an electronic circuit for controlling the detector andoutputting a signal from it, the electronic circuit to be adjusted mustbe brought into an adjustable state without inserting it in the intakeair passage when an adjustment is carried out while introducing air toflow to the air flow detecting unit. Accordingly, there has been aproblem that the adjusting equipment tends to be complex and themanufacturing process is complicated.

For adjusting detection characteristics, an adjusting device is requiredto be electrically connected to power source, ground and outputterminals, which are provided in a usual detecting device, so as tocheck characteristics of the detecting device. Because those terminalsare contained in a housing connector, the connection between theterminals and the adjusting device can be established, for example, by amethod of coupling a connector of the adjusting device to a housingconnector. However, since the housing connector is formed in variousforms, adjusting devices having various connectors in match with thehousing connector forms must be prepared and hence the adjustment worksbecome intricate. Generally, the in-connector terminals and a circuitboard are connected, for example, by wire bonding in many cases. Whileit is therefore also conceivable to connect the adjustment terminals ofthe adjusting device to bonding pads, this method requires the bondingpads to additionally have positions for connection to the adjustmentterminals of the adjusting device. If the positions for the adjustmentterminals are prepared in the bonding pads on the circuit board having areduced size, a larger restriction is imposed on a pattern layout.Alternatively, if the positions for the adjustment terminals areprepared in an area on the terminal side which is subjected to thebonding, reliability of the bonding is reduced. Further, since thepositions of the bonding pads differ depending on the types of detectingdevices, adjusting devices having various type of adjustment terminalsmust also be prepared and hence the adjustment works become intricate.

An object of the present invention is to provide a device for detectinga physical quantity, which can easily perform adjustment works and cansimplify a manufacturing process.

To achieve the above object, the present invention provides a device fordetecting a physical quantity, the device comprising a detector fordetecting a physical quantity; an electronic circuit electricallyconnected to the detector; a housing for accommodating and holding theelectronic circuit therein; and a terminal for connecting the electroniccircuit to an external device and a connector housing for surroundingthe terminal projected externally of the housing, the terminal and theconnector housing being both disposed in the housing, wherein a groovefor making a part of the terminal exposed therein is formed in a part ofa frame portion of the housing in which the terminal communicates theelectronic circuit on the inner side and the connector housing on theouter side with each other.

Also, the present invention provides a device for detecting a physicalquantity, the device comprising a detector for detecting a physicalquantity; an electronic circuit electrically connected to the detectorand outputting a signal corresponding to the physical quantity; ahousing for accommodating and holding the electronic circuit therein;and a support member for supporting the detector externally of thehousing, the support member being disposed in the housing, wherein agroove for making a part of the support member exposed therein is formedin a part of a frame portion of the housing in which the support membercommunicates the electronic circuit on the inner side and the detectoron the outer side with each other.

With those constructions, the terminal and the support member eachexposed in the groove can be employed as an adjustment terminal forobtaining output characteristics in adjustment works. As a result, theadjustment works can easily be performed and the manufacturing processcan be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an overall construction of anair flowmeter as a device for detecting a physical quantity according toa first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along the line A—A in FIG. 1.

FIG. 3 is a sectional view showing a construction of a principal part ofthe air flowmeter as the device for detecting the physical quantityaccording to the first embodiment of the present invention, the viewbeing an enlarged sectional view of an area Y1 in FIG. 2.

FIG. 4 is a sectional view showing one construction of a principal partof the air flowmeter as the device for detecting the physical quantityaccording to the first embodiment of the present invention, the viewbeing a sectional view taken along the line D—D in FIG. 3.

FIG. 5 is a sectional view showing another construction of the principalpart of the air flowmeter as the device for detecting the physicalquantity according to the firsts embodiment of the present invention,the view being a sectional view taken along the line D—D in FIG. 3.

FIG. 6 is a sectional view showing a construction of a principal part ofthe air flowmeter as the device for detecting the physical quantityaccording to the first embodiment of the present invention, the viewbeing an enlarged sectional view of an area Y2 in FIG. 2.

FIG. 7 is a sectional view showing one construction of a principal partof the air flowmeter as the device for detecting the physical quantityaccording to the first embodiment of the present invention, the viewbeing a sectional view taken along the line E—E in FIG. 6.

FIG. 8 is a sectional view showing another construction of the principalpart of the air flowmeter as the device for detecting the physicalquantity according to the first embodiment of the present invention, theview being a sectional view taken along the line E—E in FIG. 6.

FIG. 9 is a cross-sectional view for explaining a mounted state inadjustment of characteristics of the air flowmeter as the device fordetecting physical quantity according to the first embodiment of thepresent invention.

FIG. 10 is a sectional view taken along the line B—B in FIG. 9, lookingin the direction of arrow.

FIG. 11 is a partial sectional view showing a construction of a contactsection of a probe used for adjustment of characteristics of an airflowmeter according to one embodiment of the present invention.

FIG. 12 is a circuit diagram for use in works for adjustingcharacteristics of the air flowmeter according to the one embodiment ofthe present invention.

FIG. 13 is an explanatory view for explaining works for measuringresistance of a resistor used in the air flowmeter according to the oneembodiment of the present invention.

FIG. 14 is a sectional view showing a construction of a second exampleof the principal part of the air flowmeter as the device for detectingthe physical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y1 in FIG. 2.

FIG. 15 is a sectional view showing one construction of the secondexample of the principal part of the air flowmeter as the device fordetecting the physical quantity according to the first embodiment of thepresent invention, the view being a sectional view taken along the lineF—F in FIG. 14.

FIG. 16 is a sectional view showing another construction of theprincipal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being a sectional view taken along the line F—F inFIG. 14.

FIG. 17 is a sectional view showing a construction of a third example ofthe principal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y1 in FIG. 2.

FIG. 18 is a sectional view showing a construction of a second exampleof the principal part of the air flowmeter as the device for detectingthe physical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2.

FIG. 19 is a sectional view showing a construction of a third example ofthe principal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2.

FIG. 20 is a sectional view showing a construction of a third example ofa principal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being a sectional view taken along the line G—G inFIG. 19.

FIG. 21 is a sectional view showing another construction of theprincipal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being a sectional view taken along the line G—G inFIG. 19 similarly to FIG. 20.

FIG. 22 is a sectional view showing a construction of a fourth exampleof the principal part of the air flowmeter as the device for detectingthe physical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2.

FIG. 23 is a sectional view showing a construction of a fifth example ofthe principal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2.

FIG. 24 is a sectional view showing a construction of a sixth example ofthe principal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2.

FIG. 25 is a cross-sectional view showing an overall construction of anair flowmeter as a device for detecting a physical quantity according toa second embodiment of the present invention.

FIG. 26 is an enlarged sectional view taken along the line H—H in FIG.25.

FIG. 27 is a cross-sectional view showing an overall construction of anair flowmeter as a device for detecting a physical quantity according toa third embodiment of the present invention.

FIG. 28 is a cross-sectional view showing an overall construction of anair flowmeter as a device for detecting a physical quantity according toa fourth embodiment of the present invention.

FIG. 29 is a plan view showing an overall construction of a pressuremeasuring device as a device for detecting a physical quantity accordingto a fourth embodiment of the present invention.

FIG. 30 is a longitudinal sectional view taken along the line J—J inFIG. 29.

FIG. 31 is a system diagram showing a construction of an engine controlsystem using the device for detecting the physical quantity according toeach of the embodiments of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A construction of a device for detecting a physical quantity accordingto a first embodiment of the present invention will be described belowwith reference to FIGS. 1 to 24. Note that the following description ismade of the device for detecting the physical quantity, taking as anexample an air flowmeter with a resistance heater.

To begin with, an overall construction of the air flowmeter as thedevice for detecting the physical quantity according to this embodimentwill be described with reference to FIGS. 1 and 2.

FIG. 1 is a cross-sectional view showing an overall construction of anair flowmeter as a device for detecting a physical quantity according toa first embodiment of the present invention, and FIG. 2 is an enlargedsectional view taken along the line A—A in FIG. 1. Note that, in FIGS. 1and 2, the same characters denote the same components.

As shown in FIG. 1, an air flowmeter 100 is mounted to a main passagebody 10. A main air passage MP is formed in the main passage body 10,and intake air for an internal combustion engine is introduced in thedirection of an arrow X, for example. A fore end of the air flowmeter100 is inserted to project into the main air passage MP.

The air flowmeter 100 comprises a housing 110 and an auxiliary passagebody 120. The housing 110 and the auxiliary passage body 120 are eachformed as a molded member made of an insulating material. A projection121 of the auxiliary passage body 120 is fitted to a groove 111 formedin the housing 110, and the auxiliary passage body 120 is fixed to thehousing 110 by using an adhesive. The groove 111 is formed as a slotpenetrating through the housing 110. An auxiliary air passage BP isformed in the auxiliary passage body 120. A part of the intake airflowing through the main air passage MP flows into the auxiliary airpassage BP from an inlet port BPin and flows out of if from an outletport BPout.

An intake-air temperature sensor 130, a resistance heater 134, and atemperature sensitive resistor 132 are disposed in the auxiliary airpassage BP. The intake-air temperature sensor 130 is used to detect atemperature of intake air. The temperature sensitive resistor 132 isused to detect a temperature of intake air and to compensate an amountof intake air measured by the resistance heater 134. The resistanceheater 134 is used to detect an air flow rate. In the auxiliary airpassage BP, the intake-air temperature sensor 130, the temperaturesensitive resistor 132, and the resistance heater 134 are arranged inthis order from the upstream side. The order in arrangement of thosecomponents may be changed to any other suitable order. Additionally, theintake-air temperature sensor 130 is not always essential.

Opposite ends of the intake-air temperature sensor 130, the temperaturesensitive resistor 132, and the resistance heater 134 are connected toand fixedly supported by one ends of conductive support members 130A,130B, 132A, 132B, 134A and 134B. The conductive support members 130A,130B, 132A, 132B, 134A and 134B are fixedly supported to the housing 110by insert molding. In the state in which the auxiliary passage body 120is not mounted to the housing 110, all the conductive support members130A, 130B, 132A, 132B, 134A and 134B are each exposed in the flat formin an area corresponding to the groove 111. Note that the exposed partis not necessarily limited to the flat form. When mounting the auxiliarypassage body 120, the parts of the conductive members exposed in thegroove 111 are covered with an adhesive. Because of the conductivemembers 130, 132, and 134 each being exposed in the flat form in thegroove 111, the conductive members will not interfere with applicationof an adhesive when a product is assembled. Also, because of the groove111 being linearly extended, a resulting structure allows the adhesiveto be applied with ease. Hence, automation of the assembly works can bepromoted and the assembly efficiency can be improved. Further, whenforming the housing as an insert-molded component in which theconductive members are inserted, moldability of the housing can beimproved because it is possible to support intermediate portions of theinserted conductive members.

An electronic circuit 140 is disposed inside a frame-shaped portion ofthe housing 110. The electronic circuit 140 includes therein a circuitfor detecting an air flow rate, a circuit for compensating the detectedair flow rate in accordance with an intake air temperature, asensitivity compensating circuit for compensating sensitivity, and anadjustment circuit for adjusting the 0-span. A plurality of connectingterminals of the electronic circuit 140 are connected respectively tothe other ends of the conductive support members 130A, 130B, 132A, 132B,134A and 134B by wire bonding indicated by WB1. Also, conductiveconnector terminals 142A, 142B, 142C, 142D and 142E are fixedlysupported in an upper portion of the housing 110 by insert molding. Oneends of the conductive connector terminals 142A, 142B, 142C, 142D and142E are connected respectively to a plurality of output terminals ofthe electronic circuit 140 by wire bonding indicated by WB2. The otherends of the conductive connector terminals 142A, 142B, 142C, 142D and142E are projected to be exposed inside a housing connector 113 which isformed integrally with the housing 110. By connecting an externalconnector to the housing connector 113, the detected air flow rate canbe taken out to the outside.

One example of the conductive connector terminals will now be described.By way of example, the conductive connector terminal 142A is a positiveterminal of the intake-air temperature sensor, the connector terminal142B is a negative terminal of the intake-air temperature sensor, theconnector terminal 142C is a characteristic output terminal, theconnector terminal 142D is a ground terminal, and the connector terminal142E is a power supply terminal. Among those connector terminals, theconnector terminals 142C, 142D and 142E are ones that are not speciallyprovided, but are always provided in the ordinary detecting device.Also, the connector terminals 142A, 142B are ones used for theintake-air temperature sensor, and hence are not always essential. Inother words, the conductive connector terminals described herein areones that are necessarily provided in the ordinary detecting device. Itis a matter of course that the above-described terminal arrangement maybe changed to any other suitable order.

A groove 112 is formed in the housing 110. In the state in which acover, described later with reference to FIG. 2, is not attached to thehousing 110, the conductive connector terminals 142A, 142B, 142C, 142Dand 142E are each partly exposed in the flat form in an areacorresponding to the groove 112. Note that the exposed part is notnecessarily limited to the flat form. The parts of the conductiveconnector terminals exposed in the groove 112 are covered with anadhesive when the cover is attached in place.

As shown in FIG. 2, a cover 150 is fixedly attached to one surface ofthe housing 110. The cover 150 has an edge portion 151 bent along itsouter periphery. The edge portion 151 is inserted in the groove 112,having a rectangular ring shape, of the housing 110, and the cover 150is fixed to the housing 110 by an adhesive.

Further, a metal-made base 160 is fixedly mounted to both the othersurface of the housing 110 and an open side surface of the auxiliarypassage body 120. The base 160 is properly positioned by pressingprojections 122A, 122B provided on the auxiliary passage body 120 andprojections 114A, 114B provided on the housing 110 into correspondingrecesses formed in the base. Thereafter, the base 160 is fixedly mountedin place using an adhesive. A manner of realizing the combined structureis not always limited to pressing, but may be, for example, fitting. Theelectronic circuit 140 is mounted to the base 160 such that theelectronic circuit 140 is accommodated in the frame-shaped portion ofthe housing 110. Since the base 160 is made of a metal having goodthermal conductivity, heat generated from the electronic circuit 140 isdissipated to the airflow passing through the main air passage MP forcooling the electronic circuit 140. Additionally, the metal-made base160 is also able to shield the electronic circuit 140.

Next, a detailed structure of an area Y1 in FIG. 2 will be describedwith reference to FIGS. 3 and 4.

FIG. 3 is a sectional view showing a construction of a principal part ofthe air flowmeter as the device for detecting the physical quantityaccording to the first embodiment of the present invention, the viewbeing an enlarged sectional view of an area Y1 in FIG. 2. FIG. 4 is asectional view showing one construction of a principal part of the airflowmeter as the device for detecting the physical quantity according tothe first embodiment of the present invention, the view being asectional view taken along the line D—D in FIG. 3. Note that the samecharacters as those in FIGS. 1 and 2 denote the same components.

The groove 112 is formed in the housing 110. The groove 112 is providedin a part of the frame-shaped portion of the housing 110 formed tosurround the electronic circuit 140. More specifically, in the structureof this embodiment, the groove 112 is defined as a groove in which thecover 150 covering the open side surface of the housing 110 is bonded tothe housing 110. In the state in which the cover 150 is not attached tothe housing 110, the conductive connector terminal 142D is partlyexposed in the flat form in the area corresponding to the groove 112.The edge portion 151 at the outer periphery of the cover 150 is insertedin the rectangular ring-shaped groove 112 of the housing 110, and thecover 150 is fixed to the housing 110 by an adhesive BA. The part of theconductive connector terminal 142D exposed in the groove 112 is coveredwith the adhesive BA when the cover 150 is attached in place. Further,in the structure of this embodiment, the groove 112 has abottom-equipped channel structure so that the connector terminals 142A,. . . , 142E of the conductive members are exposed in the flat form tolie on a straight line. With such a structure, therefore, stagnant airdoes not generate in the adhesive BA when the parts of the connectorterminals exposed in the groove 112 are covered with the adhesive BA.

The projection 114B provided on the housing 110 is pressed into a recess161B formed in the base 160, whereby base 160 is properly positioned.Thereafter, the base 160 is fixedly mounted in place using an adhesive.A manner of realizing the combined structure is not always limited topressing, but may be, for example, fitting.

Another example of the detailed structure of the area Y1 in FIG. 2 willnow be described with reference to FIG. 5.

FIG. 5 is a sectional view showing another construction of the principalpart of the air flowmeter as the device for detecting the physicalquantity according to the first embodiment of the present invention, theview being a sectional view taken along the line D—D in FIG. 3 similarlyto FIG. 4. Note that the same characters as those in FIGS. 1 and 2denote the same components.

As is apparent from comparison with FIG. 4, one flat surface of theconductive connector terminal 142A is not completely exposed, and arecess 110 a is formed in a housing 110′. On the other hand, aprojection 151 a is provided at a fore end of an edge portion 151′ of acover 150′ in a position corresponding to the recess 110 a. Whenattaching the cover 150′ to the housing 110′, the projection 151 a isfitted to the recess 110 a.

Next, a detailed structure of an area Y2 in FIG. 2 will be describedwith reference to FIGS. 6 and 7.

FIG. 6 is a sectional view showing a construction of a principal part ofthe air flowmeter as the device for detecting the physical quantityaccording to the first embodiment of the present invention, the viewbeing an enlarged sectional view of an area Y2 in FIG. 2. FIG. 7 is asectional view showing one construction of a principal part of the airflowmeter as the device for detecting the physical quantity according tothe first embodiment of the present invention, the view being asectional view taken along the line E—E in FIG. 6. Note that the samecharacters as those in FIGS. 1 and 2 denote the same components.

The groove 111 is formed in the housing 110 so as to penetrate it. Thegroove 111 is provided in a part of the frame-shaped portion of thehousing 110 formed to surround the electronic circuit 140. Morespecifically, in the structure of this embodiment, the groove .111 isdefined as a slot in which the auxiliary passage body 120 covering theopen side surface of the housing 110 is bonded to the housing 110. Inthe state in which the auxiliary passage body 120 is not attached to thehousing 110, the conductive support member 134A is entirely exposed inthe flat form in the area corresponding to the groove 111. Theprojection 121 at the outer periphery of the auxiliary passage body 120is inserted in the groove 111 of the housing 110, and the auxiliarypassage body 120 is fixed to the housing 110 by an adhesive BA. The partof the conductive member 134A exposed in the groove 111 is covered withthe adhesive BA when the auxiliary passage body 120 is mounted to thehousing 110.

A projection 140A provided on the housing 110 is pressed into a recess161A formed in the base 160, whereby the base 160 is properlypositioned. Thereafter, the base 160 is fixedly mounted in place usingan adhesive. A manner of realizing the combined structure is not alwayslimited to pressing, but may be, for example, fitting.

Another example of the detailed structure of the area Y2 in FIG. 2 willnow be described with reference to FIG. 8.

FIG. 8 is a sectional view showing another construction of the principalpart of the air flowmeter as the device for detecting the physicalquantity according to the first embodiment of the present invention, theview being a sectional view taken along the line E—E in FIG. 6 similarlyto FIG. 7. Note that the same characters as those in FIGS. 1 and 2denote the same components.

As is apparent from comparison with FIG. 7, the conductive supportmember 134A is placed in a slit-like groove 110 b formed in a housing110′. On the other hand, a projection 121′ is provided on an auxiliarypassage body 120′ in the form of one of comb teeth-like projections.When attaching the auxiliary passage body 120′ to the housing 110′ theprojection 121′ is fitted to the groove 110 b.

Next, a method of adjusting characteristics of the air flowmeter as thedevice for detecting the physical quantity according to this embodimentwill be described with reference to FIGS. 9 to 12.

A description is first made of a mounted state of the air flowmeteraccording to this embodiment in adjustment of characteristics of the airflowmeter with reference to FIGS. 9 and 10.

FIGS. 9 and 10 are each an explanatory view for explaining a mountedstate in adjustment of characteristics of the air flowmeter as thedevice for detecting physical quantity according to the first embodimentof the present invention. FIG. 9 is a cross-sectional view and FIG. 10is a sectional view taken along the line B—B in FIG. 9, looking in thedirection of arrow. Note that the same characters as those in FIGS. 1and 2 denote the same components.

As shown in FIG. 9, the air flowmeter 100 comprises the housing 110, theauxiliary passage body 120, the resistance heater 134, the temperaturesensitive resistor 132, the intake-air temperature sensor 130, theelectronic circuit 140, and the base 160. When performing the adjustmentof characteristics, the cover 150 shown in FIG. 2 is not attached to thehousing 110. Therefore, the conductive connector terminals 142A, . . . ,142E are partly exposed in the flat form in the areas corresponding tothe groove 112 of the housing 110. Also, at this point of time, theexposed parts of the conductive connector terminals are not covered withthe adhesive BA.

The auxiliary passage body 120 of the air flowmeter 100, which is in thestate of the cover 150 being not attached, is inserted in acharacteristic adjustment passage AP. The electronic circuit 140 and theconnector terminals 142A, . . . , 142E are projected externally of thecharacteristic adjustment passage AP. An airflow for characteristicadjustment flows through the characteristic adjustment passage AP asindicated by an arrow X1.

Subsequently, as shown in FIG. 10, a fore end of a characteristicadjustment probe PD is brought into contact with the part of theconductive connector terminal 142D, which is exposed in the flat form inthe area corresponding to the groove 112 of the housing 110, forelectrical connection between the conductive connector terminal 142D andthe characteristic adjustment probe PD.

Next, a description is made of a construction of a contact section of aprobe used for adjustment of characteristics of the air flowmeteraccording to this embodiment with reference to FIG. 11.

FIG. 11 is a partial sectional view showing a construction of a contactsection of a probe used for adjustment of characteristics of an airflowmeter according to one embodiment of the present invention. Notethat the same characters as those in FIGS. 1 and 2 denote the samecomponents.

The conductive connector terminals 142A, 142B, 142C, 142D and 142E arefixedly supported in the housing 110 by insert molding. Since the groove112 is formed in the housing 110, respective parts 142A′, 142B′, 142C′,142D′ and 142E′ of the conductive connector terminals 142A, 142B, 142C,142D and 142E are exposed in the flat form in the areas corresponding tothe groove 112 in the state in which the cover is not attached to thehousing 110. The exposed parts 142A′, 142B′, 142C′, 142D′ and 142E′ ofthe connector terminals 142A, 142B, 142C, 142D and 142E each have awidth w1 of, e.g., 2.7 mm. The width w1 can be optionally selected fromthe range of, e.g., 0.5 to 3 mm. Gaps g1, g2 between relevant adjacenttwo of the exposed parts 142A′, 142B′, 142C′, 142D′ and 142E′ of theconductive connector terminals 142A, 142B, 142C, 142D and 142E arerespectively 1 mm and 2 mm, for example.

One ends of the conductive connector terminals 142A, 142B, 142C, 142Dand 142E are projected to be exposed inside the housing connector 113which is formed integrally with the housing 110. The shape anddimensions of the housing connector 113 vary depending on customer'sdemands. However, since the width w1 of and the gaps g1, g2 between theexposed parts 142A′, 142B′, 142C′, 142D′ and 142E′ of the connectorterminals 142A, 142B, 142C, 142D and 142E are not included in customer'sspecifications, they can be set to have any desired shapes anddimensions. In this embodiment, therefore, the groove 112 is formed in apart of the housing 110 and the shapes and dimensions of the exposedparts 142A′, 142B′, 142C′, 142D′ and 142E′ of the connector terminals142A, 142B, 142C, 142D and 142E, which are exposed in the groove, arestandardized regardless of the customer's specifications. Accordingly,the dimensions and shapes of probes PD shown in FIG. 10 can be preparedin accordance with unified standards.

Next, works for adjusting characteristics of the air flowmeter accordingto this embodiment with reference to FIG. 12.

FIG. 12 is a circuit diagram for use in works for adjustingcharacteristics of the air flowmeter according to the one embodiment ofthe present invention. Note that the same characters as those in FIGS. 1and 2 denote the same components.

The electronic circuit 140 comprises a bridge circuit 140A and anamplification circuit 140B. The resistance heater 134 and thetemperature sensitive resistor 132 are both connected to the bridgecircuit 140A. A signal corresponding to the air flow rate detected bythe bridge circuit 140A is amplified by the amplification circuit 140B.A characteristic adjusting section 140B-T is included in theamplification circuit 140B. The characteristic adjusting section 140B-Tis able to adjust the sensitivity and 0-span of the air flow rate signaloutputted from the amplification circuit 140B by trimming resistance,etc.

Probes PC, PD and PE are connected respectively to the exposed parts142C′, 142D′ and 142E′ of the connector terminals 142C, 142D and 142E.The probes PC, PD and PE are also connected to a characteristicadjusting device. During the adjustment of characteristics, probe outputsignals are read while varying the flow rate of air flowing through thecharacteristic adjustment passage AP. Then, the adjustment ofcharacteristics is performed by trimming resistance, etc. in thecharacteristic adjusting section 140B-T so that the sensitivity and0-span of the air flow rate signal are each held in a preset range. As aresult, the adjustment works can easily be performed and themanufacturing process can be simplified with this embodiment.

When mounting the auxiliary passage body 120, the parts of theconductive support members 130A, 130B, 132A, 132B, 134A and 134B exposedin the groove 111 are totally covered with an adhesive. Hitherto, therehas been a problem that gas and liquids enter and flow out through smallgaps between the molded resin of the housing and the conductive supportmembers, which electrically connect the flow rate detecting sectiondisposed in the intake pipe and the electronic circuit, thus resultingin shortening of the product life and a reduction of the reliability.With this embodiment, however, because the conductive support members130A, 130B, 132A, 132B, 134A and 134B are covered with a resin such asan adhesive, it is possible to prevent gas and liquids from entering andflowing out through the small gaps between the support members and theresin, and hence to improve the reliability.

Next, a description is made of works for measuring resistance of aresistor used in the air flowmeter according to this embodiment withreference to FIG. 13.

FIG. 13 is an explanatory view for explaining works for measuringresistance of a resistor used in the air flowmeter according to the oneembodiment of the present invention. FIG. 13 is a sectional view takenalong the line C—C in FIG. 1. Note that the same characters as those inFIGS. 1 and 2 denote the same components.

Respective both ends of the intake-air temperature sensor 130, thetemperature sensitive resistor 132, and the resistance heater 134 areconnected to the one ends of the conductive support members 130A, 130B,132A, 132B, 134A and 134B and fixedly supported by them. The conductivesupport members 130A, 130B, 132A, 132B, 134A and 134B are fixedly heldin the housing 110 by insert molding. When the auxiliary passage body120 is not attached to the housing 110, parts 130A′, 130B′, 132A′, 134A′and 134B′ of all the conductive support members 130A, 130B, 132A, 132B,134A and 134B are exposed in the flat form in the areas corresponding tothe groove 111. It is here to be noted that the support members 132B and134A are connected in common to the exposed part 134A′. Further, theconductive support members 130A′, 130B′, 132A′, 134A′ and 134B′ exposedin the groove 111 have a plate-like sectional shape, and their oppositesurfaces parallel to open surfaces of the groove are exposed in the flatform. The parts of the conductive members exposed in the groove 111 arecovered with an adhesive when the auxiliary passage body 120 is mountedin place.

Resistance values of the resistance members, such as the intake-airtemperature sensor 130, the temperature sensitive resistor 132, and theresistance heater 134, must be measured in advance. To that end, theresistance values of the resistance members 130, 132 and 134 aremeasured by a 4-terminal method using probes P1, P2, P3 and P4. In theillustrated example, the resistance value of the resistance heater 134is measured by contacting the probes P1, P2 with one of the resistanceheater 134 and contacting the probes P3, P4 with the other end thereof.Because the groove 111 is formed as a through hole in the housing 110,the probes P1, P2, P3 and P4 can be brought into contact with theexposed parts 134A′, 134B′ of the support member from both sides. It isthus possible to measure the resistance value with high accuracy byemploying the 4-terminal method, and to realize a reduction of thedevice size.

Next, a detailed structure of a second example of the area Y1 in FIG. 2will be described with reference to FIGS. 14 and 15.

FIG. 14 is a sectional view showing a construction of a second exampleof the principal part of the air flowmeter as the device for detectingthe physical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y1 in FIG. 2. FIG. 15 is a sectional view showing oneconstruction of the second example of the principal part of the airflowmeter as the device for detecting the physical quantity according tothe first embodiment of the present invention, the view being asectional view taken along the line F—F in FIG. 14. Note that the samecharacters as those in FIGS. 1, 2 and 3 denote the same components.

A groove 112A is formed in a housing 110A. The groove 112A is in theform of a through hole penetrating the housing 110A. In the state inwhich the cover 150 is not attached to the housing 110A, the conductiveconnector terminal 142D is entirely exposed in the flat form in an areacorresponding to the groove 112A. An edge portion 151 at an outerperiphery of the cover 150 is inserted in the rectangular ring-shapedgroove 112A of the housing 110A, and the cover 150 is fixed to thehousing 110A by an adhesive BA. The part of the conductive terminal 142Dexposed in the groove 112A is covered with the adhesive BA when thecover 150 is attached in place.

A projection 114B provided on the housing 110A is pressed into a recess161B formed in the base 160, whereby the base 160 is properlypositioned. Thereafter, the base 160 is fixedly mounted in place usingan adhesive. A manner of realizing the combined structure is not alwayslimited to pressing, but may be, for example, fitting.

Another example of the detailed structure of the area Y1 in FIG. 2 willnow be described with reference to FIG. 16.

FIG. 16 is a sectional view showing another construction of theprincipal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being a sectional view taken along the line F—F inFIG. 14 similarly to FIG. 15. Note that the same characters as those inFIGS. 1 and 2 denote the same components.

As is apparent from comparison with FIG. 15, one flat surface of theconductive connector terminal 142A is not completely exposed, and a slot110 a′ is formed in a housing 110A′. On the other hand, a projection 151a is provided at a fore end of an edge portion 151′ of a cover 150′ in aposition corresponding to the slot 110 a′. When attaching the cover 150′to the housing 110A′, the projection 151 a is pressed into the slot 110a′.

Next, a detailed structure of a third example of the area Y1 in FIG. 2will be described with reference to FIG. 17.

FIG. 17 is a sectional view showing a construction of a third example ofthe principal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y1 in FIG. 2. Note that the same characters as those in FIGS. 1to 3 and 14 denote the same components.

A groove 112A is formed in a housing 110A. The groove 112A is in theform of a through hole penetrating the housing 110A. In the state inwhich the cover 150 is not attached to the housing 110A, the conductiveconnector terminal 142D is entirely exposed in the flat form in an areacorresponding to the groove 112A. The edge portion 151 at the outerperiphery of the cover 150 is inserted in the rectangular ring-shapedgroove 112A of the housing 110A, and the cover 150 is fixed to thehousing 110A by an adhesive BA. The part of the conductive terminal 142Dexposed in the groove 112A is covered with the adhesive BA when thecover 150 is attached in place.

A projection 114B provided on the housing 110A is pressed into a recess161B formed in a base 160A, whereby the base 160A is properlypositioned. Thereafter, the base 160A is fixedly mounted in place usingan adhesive. A manner of realizing the combined structure is not alwayslimited to pressing, but may be, for example, fitting. Further, the base160A has a projection 162 and is properly positioned with the projection162 pressed into the groove 112A. A manner of realizing the combinedstructure is not always limited to pressing, but may be, for example,fitting.

Next, a detailed structure of a second example of the area Y2 in FIG. 2will be described with reference to FIG. 18.

FIG. 18 is a sectional view showing a construction of a second exampleof the principal part of the air flowmeter as the device for detectingthe physical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2. Note that the same characters as those in FIGS.1, 2 and 6 denote the same components.

The groove 111 is formed in the housing 110 so as to penetrate it. Inthe state in which the auxiliary passage body 120 is not attached to thehousing 110, the conductive support member 134A is entirely exposed inthe flat form in the area corresponding to the groove 111. Theprojection 121 at the outer periphery of the auxiliary passage body 120is inserted in the groove 112 of the housing 110, and the auxiliarypassage body 120 is fixed to the housing 110 by an adhesive BA. The partof the conductive member 134A exposed in the groove 111 is covered withthe adhesive BA when the auxiliary passage body 120 is mounted to thehousing 110.

A projection 114A provided on the housing 110 is pressed into a recess161A formed in a base 160A, whereby the base 160A is properlypositioned. Thereafter, the base 160A is fixedly mounted in place usingan adhesive. A manner of realizing the combined structure is not alwayslimited to pressing, but may be, for example, fitting. Further, the base160A has a projection 162A and is properly positioned with theprojection 162A pressed into the groove 111. A manner of realizing thecombined structure is not always limited to pressing, but may be, forexample, fitting.

The adhesive BA explained in this embodiment is an adhesive having athixotropy ratio greater than 1. In an assembly process, after applyingthe adhesive BA to the projection 162A, the base 160A is assembled tothe housing 110. Then, the adhesive BA is poured into the groove 111,and the auxiliary passage body 120 is mounted to the groove 111. Such anassembly process provides a structure that the conductive supportmembers can easily be covered with the adhesive BA and air is preventedfrom stagnating in the adhesive BA.

Next, a detailed structure of a third example of the area Y2 in FIG. 2will be described with reference to FIGS. 19 and 20.

FIG. 19 is a sectional view showing a construction of a third example ofthe principal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2. FIG. 20 is a sectional view showing aconstruction of the third example of the principal part of the airflowmeter as the device for detecting the physical quantity according tothe first embodiment of the present invention, the view being asectional view taken along the line G—G in FIG. 19. Note that the samecharacters as those in FIGS. 1, 2 and 6 denote the same components.

A groove 111A is formed in a housing 110B. Unlike the groove 111, shownin FIG. 4, penetrating through the housing, the groove 111A is abottom-equipped hole not penetrating through the housing. In the statein which the auxiliary passage body 120 is not attached to the housing110B, the conductive support member 134A is partly exposed in the flatform in the area corresponding to the groove 111A. The projection 121 atthe outer periphery of the auxiliary passage body 120 is inserted in thegroove 111A of the housing 110B, and the auxiliary passage body 120 isfixed to the housing 110B by an adhesive BA. The part of the conductivemember 134A exposed in the groove 111A is covered with the adhesive BAwhen the auxiliary passage body 120 is mounted to the housing 110B.

The projection 114A provided on the housing 110B is pressed into therecess 161A formed in the base 160A, whereby the base 160A is properlypositioned. Thereafter, the base 160A is fixedly mounted in place usingan adhesive. A manner of realizing the combined structure is not alwayslimited to pressing, but may be, for example, fitting.

Another example of the detailed structure of the area Y2 in FIG. 2 willnow be described with reference to FIG. 21.

FIG. 21 is a sectional view showing another construction of theprincipal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being a sectional view taken along the line G—G inFIG. 19 similarly to FIG. 20. Note that the same characters as those inFIGS. 1 and 2 denote the same components.

As is apparent from comparison with FIG. 20, the conductive supportmember 134A is disposed to locate in a recess 110 c formed in a housing110B′. On the other hand, a projection 121 c is provided at a fore endof an edge portion 121′ of an auxiliary passage body 120′ in a positioncorresponding to the recess 110 c. When attaching the auxiliary passagebody 120′ to the housing 110B′, the projection 121 c is pressed into therecess 110 c.

Next, a detailed structure of a fourth example of the area Y2 in FIG. 2will be described with reference to FIG. 22.

FIG. 22 is a sectional view showing a construction of a fourth exampleof the principal part of the air flowmeter as the device for detectingthe physical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2. Note that the same characters as those in FIGS.1, 2, 6 and 12 denote the same components.

The groove 111 is formed in the housing 110 so as to penetrate it. Inthe state in which the auxiliary passage body 120 is not attached to thehousing 110, the conductive support member 134A is entirely exposed inthe flat form in the area corresponding to the groove 111. Theprojection 121 at the outer periphery of the auxiliary passage body 120is inserted in the groove 111 of the housing 110, and the auxiliarypassage body 120 is fixed to the housing 110 by an adhesive BA. The partof the conductive member 134A exposed in the groove 111 is covered withthe adhesive BA when the auxiliary passage body 120 is mounted to thehousing 110.

The projection 114A provided on the housing 110 is pressed into therecess 161A formed in the base 160A, whereby the base 160A is properlypositioned. Thereafter, the base 160A is fixedly mounted in place usingan adhesive. A manner of realizing the combined structure is not alwayslimited to pressing, but may be, for example, fitting. Further, the base160A has a projection 162A and is properly positioned with theprojection 162A pressed into the groove 111. A manner of realizing thecombined structure is not always limited to pressing, but may be, forexample, fitting.

A cover 150A is fixedly attached to one surface of the housing 110. Thecover 150A has an edge portion 151 bent along its outer periphery. Theedge portion 151 is inserted in the rectangular ring-shaped groove 112of the housing 110, and the cover 150A is fixed to the housing 110 by anadhesive. Further, a flange 152 is provided on the outer peripheral sideof the edge portion 151. The flange 152 is disposed in an overlappedrelation to a peripheral portion of the auxiliary passage body 120.Thus, because the auxiliary passage body 120 is retained in place by theflange 152, the auxiliary passage can be prevented from slipping off.

Assuming that the edge portion 151 has a length of L1, the projection121 has a length of L2, and the distance between the cover 150A and thebody 10 is L3, these parameters are set so as to satisfy L1>L3 and L1<L2in this embodiment. This layout can contribute to preventing theslipping-off of the auxiliary passage.

Next, a detailed structure of a fifth example of the area Y2 in FIG. 2will be described with reference to FIG. 23.

FIG. 23 is a sectional view showing a construction of a fifth example ofthe principal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2. Note that the same characters as those in FIGS.1, 2, 6, 18 and 22 denote the same components.

The groove 111 is formed in the housing 110 so as to penetrate it. Inthe state in which an auxiliary passage body 120A is not attached to thehousing 110, the conductive support member 134A is entirely exposed inthe flat form in the area corresponding to the groove 111. A projection121 at an outer periphery of the auxiliary passage body 120A is insertedin the groove 111 of the housing 110, and the auxiliary passage body120A is fixed to the housing 110 by an adhesive BA. The part of theconductive member 134A exposed in the groove 111 is covered with theadhesive BA when the auxiliary passage body 120A is mounted to thehousing 110.

The projection 114A provided on the housing 110 is pressed into therecess 161A formed in the base 160A, whereby the base 160A is properlypositioned. Thereafter, the base 160A is fixedly mounted in place usingan adhesive. A manner of realizing the combined structure is not alwayslimited to pressing, but may be, for example, fitting. Further, the base160A has a projection 162A and is properly positioned with theprojection 162A pressed into the groove 111. A manner of realizing thecombined structure is not always limited to pressing, but may be, forexample, fitting.

A cover 150B is fixedly attached to one surface of the housing 110. Thecover 150B has an edge portion 151 bent along its outer periphery. Theedge portion 151 is inserted in the rectangular ring-shaped groove 112of the housing 110, and the cover 150B is fixed to the housing 110 by anadhesive BA. Further, a flange 152 is provided on the outer peripheralside of the edge portion 151. The flange 152 is disposed in anoverlapped relation to a peripheral portion of the auxiliary passagebody 120A. The flange 152 has a projection 152A, and the projection 152Ais fixed to a recess 122 formed in the auxiliary passage body 120A by anadhesive BA2. Thus, because the auxiliary passage body 120 is retainedin place by the flange 152, the auxiliary passage can be prevented fromslipping off. Further, the adhesives BA and BA2 used herein aredifferent kinds of adhesives. Accordingly, even if one adhesive fails todevelop a bonding ability, the other adhesive still retains a bondingability so as to prevent the slipping-off of the auxiliary passage. Inaddition, by combining this structure with the auxiliary passageslipping-off preventing mechanism described above in connection with theexample of FIG. 22, a dual auxiliary passage slipping-off preventingmechanism can be realized.

Next, a detailed structure of a sixth example of the area Y2 in FIG. 2will be described with reference to FIG. 24.

FIG. 24 is a sectional view showing a construction of a sixth example ofthe principal part of the air flowmeter as the device for detecting thephysical quantity according to the first embodiment of the presentinvention, the view being an enlarged sectional view corresponding tothe area Y2 in FIG. 2. Note that the same characters as those in FIGS.1, 2, 6 and 19 denote the same components.

A groove 111C is formed in a housing 110C. The groove 111C is formed asa hole not reaching the support member 134A. On the other hand, a groove112C is formed as a hole reaching the support member 134A. In the statein which a cover 150C is not attached to the housing 110C, therefore,the conductive support member 134A is partly exposed in the flat form inthe area corresponding to the groove 112C. The projection 121 at theouter periphery of the auxiliary passage body 120 is inserted in thegroove 112C of the housing 110C, and the auxiliary passage body 120 isfixed to the housing 110C by an adhesive BA.

The cover 150C is fixedly attached to the housing 110C. The cover 150Chas an edge portion 151C bent along its outer periphery. The edgeportion 151C is inserted in the rectangular ring-shaped groove 112C ofthe housing 110, and the cover 150C is fixed to the housing 110C by anadhesive. The part of the conductive member 134A exposed in the groove112C is covered with the adhesive BA when the cover 150C is attached inplace.

With this embodiment, as described above, when the devicecharacteristics are adjusted, the characteristic adjustment can beperformed by connecting the probes to the corresponding exposed parts ofthe connector terminals. As a result, the adjustment works can easily beperformed and the manufacturing process can be simplified.

Also, since the conductive support members exposed in the groove arecovered with the adhesive when the auxiliary passage body is mounted inplace, it is possible to prevent gas and liquids from entering andflowing out through the small gaps between the support members and theresin, and hence to improve the reliability.

Further, resistance values of the resistance members, such as theintake-air temperature sensor, the temperature sensitive resistor, andthe resistance heater, can be measured with high accuracy by utilizingthe parts of the support members exposed in the groove formed in thehousing.

A construction of a device for detecting a physical quantity accordingto a second embodiment of the present invention will be described belowwith reference to FIGS. 25 and 26. Note that the following descriptionis made of the device for detecting the physical quantity, taking as anexample an air flowmeter with a resistance heater.

FIG. 25 is a cross-sectional view showing an overall construction of anair flowmeter as a device for detecting a physical quantity according toa second embodiment of the present invention, and FIG. 26 is an enlargedsectional view taken along the line H—H in FIG. 25. Note that, in FIGS.1 and 2, the same characters denote the same components.

In this embodiment, a projection 123 is provided in a portion of anauxiliary passage body 120B at which a base 160B is mounted to theauxiliary passage body 120B. On the other hand, the base 160B has a hole163 formed in a position corresponding to the projection 123. Whenmounting the base 160B to the auxiliary passage body 120B, theprojection 123 is inserted in the hole 163 for positioning and thenfixed in place by pressing. Thus, the projection 123 serves also as apositioning pin.

The auxiliary passage body 120B is also mounted to the housing 110 withthe aid of a projection 124 and a projection 125. The projection 124 isformed as a projection extending perpendicularly to the airflow. Theprojection 125 is formed as a projection extending parallel to theairflow. By employing the projection 124 extending perpendicularly tothe airflow and fitting the projection 124 to the housing 110,resistance against the airflow is increased, thus resulting in astructure that air present in a bypass is less apt to leak through thegap between the auxiliary passage body 120B and the housing 110.Further, the auxiliary passage body 120B is avoided from rotatingrelative to the housing 110 with the provision of the projection 125extending parallel to the airflow and the projection 123 serving also asa positioning pin.

This embodiment can also provide the advantages given below. When thedevice characteristics are adjusted, the characteristic adjustment canbe performed by connecting the probes to the corresponding exposed partsof the connector terminals. As a result, the adjustment works can easilybe performed and the manufacturing process can be simplified.

Also, since the conductive support members exposed in the groove arecovered with the adhesive when the auxiliary passage body is mounted inplace, it is possible to prevent gas and liquids from entering andflowing out through the small gaps between the support members and theresin, and hence to improve the reliability.

Further, resistance values of the resistance members, such as theintake-air temperature sensor, the temperature sensitive resistor, andthe resistance heater, can be measured with high accuracy by utilizingthe parts of the support members exposed in the groove formed in thehousing.

In addition, assuming that the projection 123 has a length of L4, thedistance between the cover 150A and the body 10 is L3, and the base 160Bhas a thickness of L5, these parameters are set so as to satisfy L4>L3,L5>L3 and L4<L5. By combining this embodiment satisfying thoseconditions with the auxiliary passage slipping-off preventing mechanismdescribed above in connection with FIG. 22, the slipping-off of theauxiliary passage can be prevented with higher reliability than only theauxiliary passage slipping-off preventing mechanism described above inconnection with FIG. 22, because the upper side of the auxiliary passagebody 120B is retained by the slipping-off preventing mechanism describedabove in connection with FIG. 22 and a central portion of the auxiliaryair passage is retained by the projection 123 provided at the center ofthe auxiliary passage body 120B. Moreover, by combining the auxiliarypassage slipping-off preventing mechanism described above in connectionwith the examples of FIGS. 22 and 23, the slipping-off of the auxiliarypassage can be realized with even higher reliability.

A construction of a device for detecting a physical quantity accordingto a third embodiment of the present invention will be described belowwith reference to FIG. 27. Note that the following description is madeof the device for detecting the physical quantity, taking as an examplean air flowmeter with a resistance heater.

FIG. 27 is a cross-sectional view showing an overall construction of anair flowmeter as a device for detecting a physical quantity according toa third embodiment of the present invention.

A throttle valve 22 is disposed in a body 20 such that the throttlevalve 22 is rotatable. An air flowmeter 100 is mounted to the body 20 ata position upstream of the throttle valve 22. A main air passage MP isformed in the body 20, and intake air for an internal combustion engineis introduced, for example; in the direction of an arrow X. A fore endof the air flowmeter 100 is inserted to project into the main airpassage MP.

A construction of the air flowmeter 100 is similar to that shown in FIG.1 or 2. A part of the intake air flowing through the main air passage MPflows into an auxiliary air passage BP from an inlet port BPin and flowsout of it from an outlet port BPout. The flow rate and temperature ofthe air flowing through the auxiliary air passage BP are measured by anintake-air temperature sensor, a resistance heater, a temperaturesensitive resistor, etc., which are disposed in the auxiliary airpassage BP.

In this embodiment, as with the above embodiments, conductive supportmembers for supporting both ends of the intake-air temperature sensor,the temperature sensitive resistor, and the resistance heater areexposed in the flat form in areas corresponding to a groove 111 of ahousing 110. The parts of the conductive members exposed in the groove111 are covered with an adhesive when an auxiliary passage body 120 ismounted in place.

Further, parts of conductive connector terminals are exposed in the flatform in areas corresponding to a groove 112 formed in the housing 110.The parts of the conductive members exposed in the groove 112 arecovered with an adhesive when a cover is attached in place.

With the construction described above, when the air flowmeter is mountedto the body and the flowmeter characteristics are adjusted, thecharacteristic adjustment can similarly be performed by connecting theprobes to the corresponding exposed parts of the connector terminals. Asa result, the adjustment works can easily be performed and themanufacturing process can be simplified.

Also, since the conductive support members exposed in the groove arecovered with the adhesive when the auxiliary passage body is mounted inplace, it is possible to prevent gas and liquids from entering andflowing out through the small gaps between the support members and theresin, and hence to improve the reliability.

Further, resistance values of the resistance members, such as theintake-air temperature sensor, the temperature sensitive resistor, andthe resistance heater, can be measured with high accuracy by utilizingthe parts of the support members exposed in the groove formed in thehousing.

A construction of a device for detecting a physical quantity accordingto a fourth embodiment of the present invention will be described belowwith reference to FIG. 28. Note that the following description is madeof the device for detecting the physical quantity, taking as an examplean air flowmeter with a resistance heater.

FIG. 28 is a cross-sectional view showing an overall construction of anair flowmeter as a device for detecting a physical quantity according toa fourth embodiment of the present invention.

An air cleaner 30 comprises an upstream case member 32 having anintroduction duct to take in a flow of intake air, a downstream casemember 34 having a duct to introduce the intake air into an engine room,and a filter member 36 held by both the members 32, 34 and removing dustin the air. In the air cleaner 30, the air flowmeter 100 including theauxiliary air passage BP formed integrally therewith is mounted to thedownstream case member 34.

A construction of the air flowmeter 100 is similar to that shown in FIG.1 or 2. A part of the intake air introduced through the air cleaner 30flows into an auxiliary air passage BP from an inlet port BPin and flowsout of it from an outlet port BPout. The flow rate and temperature ofthe air flowing through the auxiliary air passage BP are measured by anintake-air temperature sensor, a resistance heater, a temperaturesensitive resistor, etc., which are disposed in the auxiliary airpassage BP.

In this embodiment, as with the above embodiments, conductive supportmembers for supporting both ends of the intake-air temperature sensor,the temperature sensitive resistor, and the resistance heater areexposed in the flat form in areas corresponding to a groove 111 of ahousing 110. The parts of the conductive members exposed in the groove111 are covered with an adhesive when an auxiliary passage body 120 ismounted in place.

Further, parts of conductive connector terminals are exposed in the flatform in areas corresponding to a groove 112 formed in the housing 110.The parts of the conductive members exposed in the groove 112 arecovered with an adhesive when a cover is attached in place.

With the construction described above, when the air flowmeter is mountedto the air cleaner and the flowmeter characteristics are adjusted, thecharacteristic adjustment can similarly be performed by connecting theprobes to the corresponding exposed parts of the connector terminals. Asa result, the adjustment works can easily be performed and themanufacturing process can be simplified.

Also, since the conductive support members exposed in the groove arecovered with the adhesive when the auxiliary passage body is mounted inplace, it is possible to prevent gas and liquids from entering andflowing out through the small gaps between the support members and theresin, and hence to improve the reliability.

Further, resistance values of the resistance members, such as theintake-air temperature sensor, the temperature sensitive resistor, andthe resistance heater, can be measured with high accuracy by utilizingthe parts of the support members exposed in the groove formed in thehousing.

A construction of a device for detecting a physical quantity accordingto a firth embodiment of the present invention will be described belowwith reference to FIGS. 29 and 30. Note that the following descriptionis made of the device for detecting the physical quantity, taking as anexample a pressure measuring device.

FIG. 29 is a plan view showing an overall construction of a pressuremeasuring device as a device for detecting a physical quantity accordingto a fifth embodiment of the present invention, and FIG. 30 is alongitudinal sectional view taken along the line J—J in FIG. 29.

As shown in FIG. 29, a pressure measuring device 200 comprises a housing210, a pressure measuring section 220, and an electronic circuit 230.The pressure measuring section 220 and the electronic circuit 230 areboth contained in the housing 210. The pressure measuring section 220comprises a semiconductor substrate, a resistor such as a semiconductorstrain gauge, and a temperature sensitive resistor for compensatingtemperature, the latter two being formed on the semiconductor substrate.The pressure measuring section 220 is fixed to the housing 210 as shownin FIG. 30. A pressure introducing port 214 is provided at a bottomportion of the housing 210. A pressure of intake air for an internalcombustion engine introduced through the pressure introducing port 214is detected by the pressure measuring section 220.

A terminal of the pressure measuring section 220 is connected to theelectronic circuit 230 by wire bonding indicated by wb3. The electroniccircuit 230 includes therein a circuit for detecting a pressure, asensitivity compensating circuit for compensating sensitivity, and anadjusting circuit for adjusting the 0-span. A plurality of connectionterminals of the electronic circuit 230 are connected respectively toconductive connector terminals 40A, 240B and 240C by wire bondingindicated by wb4. The conductive connector terminals 240A, 240B and 240Care fixedly held in the housing 210 by insert molding.

A groove 212 is formed in the housing 210. In the state in which a cover250 is not attached to the housing 210, the conductive connectorterminals 240A, 240B and 240C are each partly exposed in the flat formin an area corresponding to the groove 212. The parts of the conductivemembers exposed in the groove 212 are covered with an adhesive when thecover 250 is attached in place.

With the construction described above, also in a pressure sensor as oneexample of the device for detecting the physical quantity, when thesensor characteristics are adjusted, the characteristic adjustment canbe performed by connecting the probes to the corresponding exposed partsof the connector terminals. As a result, the adjustment works can easilybe performed and the manufacturing process can be simplified.

Also, since the conductive members exposed in the groove are coveredwith the adhesive when the cover is attached in place, it is possible toprevent gas and liquids from entering and flowing out through the smallgaps between the support members and the resin, and hence to improve thereliability.

Next, a description is made of a system construction of an enginecontrol system using the device for detecting the physical quantityaccording to each of the embodiments of the present invention withreference to FIG. 31.

FIG. 31 is a system diagram showing a construction of an engine controlsystem using the device for detecting the physical quantity according toeach of the embodiments of the present invention.

Intake air sucked through an air cleaner 30 is introduced to an enginecylinder 18 through a body 10 of an air flowmeter 100 with a resistanceheater, a suction duct 12, a throttle body 20, and a manifold 16provided with an injector 14 to which fuel is supplied. On the otherhand, gas generated in the engine cylinder 18 is exhausted through anexhaust manifold 22.

A control unit 40 calculates an optimum amount of injected fuel inaccordance with an air flow rate signal outputted from an electroniccircuit of the air flowmeter 100 with the resistance heater, a throttlevalve angle signal outputted from a throttle angle sensor 24, an oxygencontent signal outputted from an oxygen densitometer 26 provided in anintake manifold, and an engine revolution angle signal detected by anengine revolution speed sensor 28. Further, the control unit 40 injectsfuel from the injector 14, and at the same time controls an idle aircontrol valve 32.

While this example employs the air flowmeter 100, the engine may becontrolled by using the pressure sensor 200 shown in FIG. 29.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to easily performworks for adjusting a device for detecting a physical quantity and tosimplify the manufacturing process.

1. A device for detecting a physical quantity, the device comprising: adetector for detecting a physical quantity; an electronic circuitelectrically connected to said detector; a housing for accommodating andholding said electronic circuit therein; and a terminal for connectingsaid electronic circuit to an external device and a housing connectorfor surrounding one end portion of said terminal projected externally ofsaid housing, an other end portion of said terminal being disposed insaid housing, wherein a groove for making a part of said terminalexposed therein is formed in a part of a frame portion of said housing,and said terminal communicates said electronic circuit on the inside ofsaid housing with said housing connecter.
 2. A device for detecting aphysical quantity according to claim 1, wherein said terminal forconnecting said electronic circuit to said external device comprisesoutput, ground and power source terminals.
 3. A device for detecting aphysical quantity, the device comprising: a detector for detecting aphysical quantity; an electronic circuit electrically connected to saiddetector and outputting a signal corresponding to the physical quantity;a housing for accommodating and holding said electronic circuit therein;and a support member for supporting said detector externally of saidhousing, said support member being disposed in said housing, wherein agroove for making a part of said support member exposed therein isformed in a part of a frame portion of said housing, and said supportmember communicates said electronic circuit inside said housing and saiddetector outside said housing with each other.
 4. A device for detectinga physical quantity according to claim 1, wherein said terminal exposedin said groove has a plate-shaped cross-section.
 5. A device fordetecting a physical quantity according to claim 4, wherein saidterminal exposed in said groove has a cross-section exposed at bothsides parallel to an open surface of said groove.
 6. A device fordetecting a physical quantity according to claim 1, wherein afteradjusting characteristics of said device for detecting the physicalquantity by using said terminal exposed in said groove, said exposedterminal is covered with an adhesive.
 7. A device for detecting aphysical quantity according to claim 3, wherein after adjustingreference characteristics of said detector by using said support memberexposed in said groove, said exposed terminal is covered with anadhesive.
 8. A device for detecting a physical quantity according toclaim 6, wherein a part of another member is inserted in said groove,and said another member is fixedly bonded to said housing by using anadhesive.
 9. A device for detecting a physical quantity according toclaim 8, wherein said another member is a cover covering an open surfaceof said housing.
 10. A device for detecting a physical quantityaccording to of claim 1, wherein said terminal end portion disposed insaid housing is formed integrally with said housing, and said groove, inwhich said terminal is partly exposed, is formed in a part of saidhousing.
 11. A device for detecting a physical quantity according toclaim 3, wherein said support member exposed in said groove has aplate-shaped cross-section.
 12. A device for detecting a physicalquantity according to claim 11, wherein said support member exposed insaid groove has a cross-section exposed at both sides parallel to anopen surface of said groove.
 13. A device for detecting a physicalquantity according to claim 3, wherein after adjusting characteristicsof said device for detecting the physical quantity by using said supportmember exposed in said groove, said exposed support member is coveredwith an adhesive.
 14. A device for detecting a physical quantityaccording to claim 3, wherein after adjusting reference characteristicsof said detector by using said support member exposed in said groove,said exposed support member is covered with an adhesive.
 15. A devicefor detecting a physical quantity according to claim 14, wherein a partof another member is inserted in said groove, and said another member isfixedly bonded to said housing by using an adhesive.
 16. A device fordetecting a physical quantity according to claim 8, wherein said anothermember is an auxiliary passage body.
 17. A device for detecting aphysical quantity according to of claim 3, wherein said support memberdisposed in said housing is formed integrally with said housing, andsaid groove, in which said support member is partly exposed, is formedin a part of said housing.